Writing Testable JavaScript (Mocha Version)

Writing Testable JavaScript Rebecca Murphey • JS Summit 2012 ©
brianUphoto http://www.flickr.com/photos/snype451/5752753663/in/photostream/

rmurphey.com • @rmurphey • bocoup.com

Writing Testable JavaScript Rebecca Murphey • JS Summit 2012 ©
brianUphoto http://www.flickr.com/photos/snype451/5752753663/in/photostream/

you will design your code you will test your code
you will refactor your code other people will use your code there will be bugs facts of life

“do the pieces work together as expected?” integration tests

def test_no_results fill_in('q', :with => 'foobarbazbimbop') find('.btn').click
assert( page.has_selector?('#results li.no-‐results'), 'No results is shown' ) assert( find('#results').has_content?('No results found'), 'No results message is shown' ) end selenium (via ruby)

“given input x, is the output y?” unit tests

'#liked' ); var pending = false; $( '#searchForm' ).on( 'submit', function( e ) { e.preventDefault(); if ( pending ) { return; } var form = $( this ); var query = $.trim( form.find( 'input[name="q"]' ).val() ); if ( !query ) { return; } pending = true; $.ajax( '/data/search.json', { data : { q: query }, dataType : 'json', success : function( data ) { var tmpl = _.template( $('#tmpl-‐people-‐detailed').text() ); resultsList.html(tmpl({ people : data.results })); pending = false; } }); $('<li>', { 'class' : 'pending', html : 'Searching …' }).appendTo( resultsList.empty() ); });

anonymous functions, lack of structure complex, oversized functions lack of
con gurability hidden or shared state tightly coupled difficult to test

'#liked' ); var pending = false; $( '#searchForm' ).on( 'submit', function( e ) { e.preventDefault(); if ( pending ) { return; } var form = $( this ); var query = $.trim( form.find( 'input[name="q"]' ).val() ); if ( !query ) { return; } pending = true; $.ajax( '/data/search.json', { data : { q: query }, dataType : 'json', success : function( data ) { var tmpl = _.template( $('#tmpl-‐people-‐detailed').text() ); resultsList.html(tmpl({ people : data.results })); pending = false; } }); $('<li>', { 'class' : 'pending', html : 'Searching …' }).appendTo( resultsList.empty() ); }); var resultsList = $( '#results' ); var liked = $( '#liked' ); var pending = false; $( '#searchForm' ).on( 'submit', function( e ) { // ... });

'#liked' ); var pending = false; $( '#searchForm' ).on( 'submit', function( e ) { e.preventDefault(); if ( pending ) { return; } var form = $( this ); var query = $.trim( form.find( 'input[name="q"]' ).val() ); if ( !query ) { return; } pending = true; $.ajax( '/data/search.json', { data : { q: query }, dataType : 'json', success : function( data ) { var tmpl = _.template( $('#tmpl-‐people-‐detailed').text() ); resultsList.html(tmpl({ people : data.results })); pending = false; } }); $('<li>', { 'class' : 'pending', html : 'Searching …' }).appendTo( resultsList.empty() ); }); $.ajax( '/data/search.json', { data : { q: query }, dataType : 'json', success : function( data ) { var tmpl = _.template( $('#tmpl-‐people-‐detailed').text() ); resultsList.html(tmpl({ people : data.results })); pending = false; } });

setup presentation & interaction application state data/server communication

search data application state glue

use constructors to create instances support con gurability keep methods
simple don’t intermingle responsibilities guiding principles

test rst.

var liked = $( '#liked' ); var resultsList = $(
'#results' ); // ... resultsList.on( 'click', '.like', function(e) { e.preventDefault(); var name = $( this ).closest( 'li' ).find( 'h2' ).text(); liked.find( '.no-‐results' ).remove(); $( '<li>', { text: name } ).appendTo( liked ); });

test('likes constructor', function() { var likes = new app.Likes({
el : '#likes' }); assert( likes ); });

test('likes are properly displayed', function() { var likes =
new app.Likes({ el : '#likes' }); likes.add( 'Brendan Eich' ); assert( $( '#likes' ).html().match( 'Brendan Eich' ), 'Like is added' ); });

app.Likes = (function() { var Likes = function( settings
) { if (! (this instanceof Likes) ) { return new Likes( settings ); } this.$el = $( settings.el ); }; Likes.prototype.add = function( name ) { this.$el.find( '.no-‐results' ).remove(); $( '<li>', { html : name } ).appendTo( this.$el ); }; return Likes; }());

$.ajax( '/data/search.json', { data : { q: query },
dataType : 'json', success : function( data ) { var tmpl = _.template( $('#tmpl-‐people-‐detailed').text() ); resultsList.html( tmpl({ people : data.results }) ); pending = false; } });

test('results are displayed', function( done ) { var results
= new app.SearchResults({ el : '#results' }); results.set( [ { name: 'Rebecca', company: { name: 'Bocoup' }, email: 'rebecca { name: 'Dan', company: { name: 'Bocoup' }, email: 'dan@bocoup. ] ); assert.equal( $( '#results li' ).length, 2 ); assert( ! $( '#results li.no-‐results' ).length ); assert( $( '#results' ).html().match('Dan') ); assert( $( '#results' ).html().match('Rebecca') ); });

app.SearchResults = (function() { var SearchResults = function( settings
) { if (! (this instanceof SearchResults) ) { return new SearchResults( settings ); } this.$el = $( settings.el ); }; SearchResults.prototype.set = function( people ) { var $el = this.$el.empty(); return app.loadTemplate( 'people-‐detailed.tmpl' ).done(function( t ) { var html = t( { people : people } ); $el.html( html ); }); }; return SearchResults; }());

test('data is fetched from the right URL', function() {
var search = new app.Search(); var result = search.fetch('cat'); assert.equal( requests[0].url, '/data/search.json?q=cat' ); });

suite('search data', function() { var xhr, requests; setup(function()
{ xhr = sinon.useFakeXMLHttpRequest(); requests = []; xhr.onCreate = function( req ) { requests.push(req); }; }); teardown(function() { xhr.restore(); }); // ... });

test('fetch returns a promise', function() { var search =
new app.Search(); var result = search.fetch('cat'); assert( result.then, 'result is a promise' ); });

test('promise resolves with array of data', function() { var
search = new app.Search(); var result = search.fetch('cat'); requests[0].respond( 200, { "Content-‐type" : "text/json" }, JSON.stringify( { results : [ 'cat' ] } ) ); result.done(function( data ) { assert.equal( data[0], 'cat' ); }); });

app.Search = (function() { var Search = function() {
if (! (this instanceof Search) ) { return new Search(); } }; var processResults = function( resp ) { return resp.results; }; Search.prototype.fetch = function( query ) { return $.getJSON( '/data/search.json', { q : query }).pipe( processResults ); }; return Search; }());

where to start?

awesome tools grunt + qunit + phantomjs grunt-mocha grunt-jasmine sinon.js
chai.js

$ grunt init:gruntfile

/*global module:false*/ var child_process = require('child_process'); module.exports = function(grunt) {
// Project configuration. grunt.initConfig({ lint: { files: ['lib/**/*.js', 'test/**/*.js', '! test/lib/**/*.js', 'www/js/**/*.js'] }, watch: { files: [ '<config:lint.files>', 'www/templates/*.tmpl' ], tasks: 'test' }, jshint: { options: { curly: true, eqeqeq: true, immed: true, latedef: true, newcap: true, noarg: true, sub: true, undef: true, boss: true, eqnull: true, browser: true }, globals: { $ : true, _ : true, RSVP : true, app : true } }, uglify: {}, mocha: { index: [ 'test/runner/index.html' ] } }); grunt.registerTask('build-‐template-‐mocks', 'Build template mocks', function() { var obj = {}; var addFile = function(filepath, contents) { obj[ filepath.replace('templates/', '') ] = contents; }; var options = {cwd: 'www'}; grunt.file.expand(options, 'templates/*.tmpl').forEach(function(filepath) { addFile(filepath, grunt.file.read('www/' + filepath)); }); var src = 'window._templateMocks = ' + JSON.stringify(obj, null, 2) + ';'; grunt.file.write('test/fixtures/templates.js', src); }); grunt.loadNpmTasks('grunt-‐mocha'); grunt.registerTask('test', 'build-‐template-‐mocks mocha'); grunt.registerTask('default', 'lint test'); };

/*global module:false*/ var child_process = require('child_process'); module.exports = function(grunt) {
// Project configuration. grunt.initConfig({ lint: { files: ['lib/**/*.js', 'test/**/*.js', '! test/lib/**/*.js', 'www/js/**/*.js'] }, watch: { files: [ '<config:lint.files>', 'www/templates/*.tmpl' ], tasks: 'test' }, jshint: { options: { curly: true, eqeqeq: true, immed: true, latedef: true, newcap: true, noarg: true, sub: true, undef: true, boss: true, eqnull: true, browser: true }, globals: { $ : true, _ : true, RSVP : true, app : true } }, uglify: {}, mocha: { index: [ 'test/runner/index.html' ] } }); grunt.registerTask('build-‐template-‐mocks', 'Build template mocks', function() { var obj = {}; var addFile = function(filepath, contents) { obj[ filepath.replace('templates/', '') ] = contents; }; var options = {cwd: 'www'}; grunt.file.expand(options, 'templates/*.tmpl').forEach(function(filepath) { addFile(filepath, grunt.file.read('www/' + filepath)); }); var src = 'window._templateMocks = ' + JSON.stringify(obj, null, 2) + ';'; grunt.file.write('test/fixtures/templates.js', src); }); grunt.loadNpmTasks('grunt-‐mocha'); grunt.registerTask('test', 'build-‐template-‐mocks mocha'); grunt.registerTask('default', 'lint test'); }; mocha: { index: [ 'test/runner/index.html' ] }

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rmurphey.com • @rmurphey • bocoup.com

Writing Testable JavaScript (Mocha Version)

Writing Testable JavaScript (Mocha Version)

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